Brentwood is a city in Williamson County, Tennessee, United States. The population was 45,373 as of the 2020 United States census. It is a suburb of Nashville and included in the Nashville metropolitan area.

Williamson County is a county in the U.S. state of Tennessee. As of the 2020 United States census, the population was 247,726. The county seat is Franklin, and the county is located in Middle Tennessee. The county is named after Hugh Williamson, a North Carolina politician who signed the U.S. Constitution. Williamson County is part of the Nashville-Davidson–Murfreesboro–Franklin, TN Metropolitan Statistical Area. In the 19th century, tobacco and hemp were cultivated here, and planters also raised blooded livestock, including horses and cattle.